sync_source_lists_from_cmake now also looks for source files in
`sources += [ "foo.cc" ]` lines, which allows us to remove most
`# Make `gn format` not collapse this` comments.
(sync_source_lists_from_cmake doesn't look for `foo_headers += [...]`
still, so the comment is still needed in two places for that.)
No intentional behavior change.
r362702 added a test that requires clang-tidy to be linked
into libclang, so add that to the gn build.
Differential Revision: https://reviews.llvm.org/D65462
llvm-svn: 367340